Pre-charge pressure of a hydraulic accumulator needs to be periodically checked after installation in a hydraulic system to ensure operational health of the accumulator. Overtime, gas within accumulators can leak, primarily due to warn or degraded rubber diaphragms or seals that separate the gas and oil chambers within the accumulator. In some machines, hydraulic braking systems are provided that utilize gas filled accumulators which, when pressurized with fluid, allows the machine operator to apply the service brakes in the event of a primary braking system failure. Typical solutions for detecting the accumulator health involve connecting a gas pressure gauge and/or a modular kit to a gas valve of the hydraulic accumulator, when the machine is stopped and the fluid in the hydraulic accumulator is not pressurized or the accumulator is empty of fluid. The gas pressure gauge provides a reading of the pre-charge pressure. Depending on such readings, the hydraulic accumulator is either re-charged or completely overhauled or replaced. Hence, typical solutions required physically connecting the hydraulic accumulator to the pressure gauge. However, the accumulator can be located on a machine such that it is difficult to access and couple the gas pressure gauge.
In one example, German Patent Number DE102005052640 relates to a method involving determination of a difference in accumulator volume using a flow regulator with constant adjustable flow rate and an actuating valve with preset response time. The method also involves determination of pressure values before and after the fluid withdrawal from a hydraulic accumulator using a pressure sensor based on its recalled calculated accumulator volume at an empty state.